1. Field of Invention
This invention relates to a method for testing semiconductor devices having bump terminals. This invention also relates to an apparatus for testing semiconductor devices having bump terminals.
2. Description of Related Art
Ball-grid-array (BGA) type semiconductor devices, have a plurality of bump terminals arranged on their terminal surfaces. BGA-type devices have been generally tested as follows. The semiconductor devices are placed in pockets of a tray such as a customer tray. The tray is transferred to a testing apparatus. The testing apparatus has a test head. The test head has test electrodes. The bump terminals of the semiconductor devices are brought into contact with the test electrodes. Then, electrical characteristics are tested. The shape of the bump terminals, such as the height of the terminal, is also tested. Thereafter, the tested devices are grouped into categories of good ones and defective ones.
When testing electrical characteristics, the semiconductor devices are generally picked up from the tray, one by one, using a robot arm, and the picked-up device is fitted to a socket having the test electrodes of the test head.
FIGS. 1A and 1B show one example of a BGA-type semiconductor device 16. FIGS. 1A and 1B show plan views of the semiconductor device 16 from opposite directions.
A plurality of bump terminals 13 are arranged on the surface (terminal surface) 12 shown in FIG. 1B. Specifically, two rows of bump terminals 13 each having a diameter of, for example, 0.3 mm are arranged on the terminal surface 12 along the four sides at intervals of 0.5 mm in each row.
Also, as shown in FIG. 1A, the semiconductor device 16 has a mold size of, for example, 18 mm×18 mm. This size is somewhat smaller than the size of the pocket of the tray. For example, the pocket has a size of 19.3 mm×19.3 mm, and thus, the sizes of the four sides of the semiconductor device 16 are each 1.3 mm shorter than the pocket size.
One type of BGA device is called a chip-size-package (CSP) type device. CSP-type devices have recently received much attention.
FIG. 2 shows a typical example of the tolerance of the position of the outermost bump terminal 13 for a CSP-type device.
As shown in FIG. 2, the bump terminal 13 has an outer diameter of 0.3 mm±0.05 mm, while the distance between the corner of the package 15 and the center of the bump terminal 13 is X±0.2 mm, where X represents an arbitrary value depending on the type of the package. In other words, the tolerance for the distance between the corner of the package and the bump terminal 13 is larger than the tolerance for the outer diameter of the bump terminal 13.
Japanese Unexamined Patent Application Publication No. 11-287842, incorporated herein by reference in its entirety, discloses a method in which a semiconductor device is picked-up from a customer tray and transferred onto an insert of a test tray. The insert has a guide means, such as a guide hole, a guide pin, or a tapered side surface that guides the bump terminals.
Alternatively, JP 11-287842 discloses the guide means provided in a heating plate to which the semiconductor devices are transferred from the customer tray. After the heating plate heats the semiconductor devices, the devices are further transferred to a test head.
In another alternative, JP 11-287842 discloses the guide means provided in chip carriers to which the semiconductor devices are transferred from the customer tray. The chip carriers carry the semiconductor device within the test apparatus.
Japanese Unexamined Patent Application Publication No. 11-97139, incorporated herein by reference in its entirety, discloses a method to align the bump terminals with the test electrodes of a socket by vibrating and sucking the semiconductor device.